Summary

• What is Dash?
  • Use cases
  • Friendly projects
• Examples
• Alternatives
• Advantages and disadvantages
• Questions

What is Dash?

“Dash is a Python framework for building analytical web applications. No JavaScript required.”

– Dash website –

Dash: under the hood

This library is based on:

• Plotly
  • Matlplotlib
  • D3.js
  • WebGL
• Flask
• React

Dash use cases

• Monitor or examine data for datascience purpose
• Build customized business intelligence web applications

Dash-friendly libraries

• Pandas: data loading and filtering
  • .csv files and database support
  • {inner, left, right} join on your data
  • Plots accept pandas DataFrame as input data by default

Examples

Other examples

• Goldman Sachs Interactive Report
• More here

Example project

• Business process mining
• Tons of messy data
• Explore data to understand the process
• Machine learning once the process is undestood

Alternatives

• Bokeh
• d3py
• Business intelligence softwares:
  • Qlik Sense
  • Disco
  • ProM

Advantages

• Open source project: https://github.com/plotly/dash
• Plots are reactive and fast (WebGL!)
• Few tweaks are necessary to make plots look nice
• Possibility to add JavaScript and CSS files
• Based on cutting edge web technologies
• All the data processing stuff can be done in Python

Disadvantages

• Generate the HTML using Dash HTML components and Dash Core Components.
• Dash is new. Is it mature enough?
  • dash-table-experiment

Questions

Simple code example

Launch these commands from a terminal to install the Python packages:

pip install dash==0.19.0  # The core dash backend
pip install dash-renderer==0.11.1  # The dash front-end
pip install dash-html-components==0.8.0  # HTML components
pip install dash-core-components==0.14.0  # Supercharged components
pip install plotly --upgrade  # Latest Plotly graphing library

Simple code example

Create a file named app.py:

import dash
import dash_core_components as dcc
import dash_html_components as html

app = dash.Dash()

app.layout = html.Div(children=[
    html.H1(children='Hello Dash'),

    html.Div(children='''
        Dash: A web application framework for Python.
    '''),

    dcc.Graph(
        id='example-graph',
        figure={
            'data': [
                {'x': [1, 2, 3], 'y': [4, 1, 2], 'type': 'bar', 'name': 'SF'},
                {'x': [1, 2, 3], 'y': [2, 4, 5], 'type': 'bar', 'name': u'Montréal'},
            ],
            'layout': {
                'title': 'Dash Data Visualization'
            }
        }
    )
])

if __name__ == '__main__':
    app.run_server(debug=True)

Simple code example

Run the app with the following command:

python app.py